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Old 02-22-2020, 01:03 PM   #1
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Sucking air as I rev it up,.!

I had this ( air sucking sound issue / problem)as well as Misfire codes on 4,5,6
300 304 305 306 and a P1238 (secondary fuel circuit )

1.changed plugs and coils on bank 2

2. pulled intake tubes to clean TB,..which was very oily and dirty,..I then cleaned the tubes because there was oil in them( could have added just a touch to much oil with my last change) redid a couple vacuum lines put it all back together runs a little better but slow to rev and it sucks alot of air from somewhere,.did the starter fluid trick no vacuum leaks no change in idle,but it sounds like a V8 with no air cleaner when I rev it up AOS lines seem fine AOS new last year also,..?? Thanks Frank

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Old 02-22-2020, 02:07 PM   #2
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Originally Posted by flmont View Post
I had this ( air sucking sound issue / problem)as well as Misfire codes on 4,5,6
300 304 305 306 and a P1238 (secondary fuel circuit )

1.changed plugs and coils on bank 2

2. pulled intake tubes to clean TB,..which was very oily and dirty,..I then cleaned the tubes because there was oil in them( could have added just a touch to much oil with my last change) redid a couple vacuum lines put it all back together runs a little better but slow to rev and it sucks alot of air from somewhere,.did the starter fluid trick no vacuum leaks no change in idle,but it sounds like a V8 with no air cleaner when I rev it up AOS lines seem fine AOS new last year also,..?? Thanks Frank
Might have blown another AOS, I would pull all the spark plugs out & inspect for oil. If the plugs are really oily crank the engine over with the key to see how much oil comes out.
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Old 02-22-2020, 05:41 PM   #3
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Ok..I pulled bank 2 plugs and yes they were carboned up and threads were oily,.but I did not pull bank 1 but I will tomorrow,.this is the second AOS installed in 1 and a half..When I pulled my oil cap there's no change in Idle that I can tell any way..Thanks
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Old 02-23-2020, 06:00 AM   #4
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Which brand AOS are you running?
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Old 02-23-2020, 08:29 AM   #5
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P/N 996.107.023.04 oil separator. undated MAF sensor 986.606.125.01
both done 6/6/2018.
they charged 129.00 for the AOS,...and 360.00 for the MAF
then replaced AOS on 10/22/2018 under warranty

I have no idea where they bought the parts.
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Old 02-23-2020, 12:08 PM   #6
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Ok..I pulled bank 2 plugs and yes they were carboned up and threads were oily,.but I did not pull bank 1 but I will tomorrow,.this is the second AOS installed in 1 and a half..When I pulled my oil cap there's no change in Idle that I can tell any way..Thanks
If the AOS is bad... or going bad... when you try to remove the oil cap it will be challenging given the suction. I learned on these pages that's a sign of a bad/failed AOS.

Now... my AOS has ~ 13K on it and, last month when I tested it (for the heck of it)... the oil cap came off without struggling but... with the cap removed it started idling differently than normal.

That when you remnove your oil cap and notice no changes in the engine running may be a sign, for wiser minds, that something else is in order to be checked. Hang in there. Someone will land on it for you.
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Last edited by Starter986; 02-24-2020 at 02:28 AM.
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Old 02-23-2020, 04:38 PM   #7
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Via 101 projects,I disconnected the AOS tube and plugged each end and YEP,..the sucking noise was gone,.still ran a bit rough tho but at least that loud sucking noise is gone,.And there was oil in that tube going to my newly cleaned TB,...I hope the Porsche brand is the best replacement part,.

why such a complicated process, Why cant you just run a tube from Case to TB,.?? Frank

PS oil cap came of easy,.but the intake side sure had some vacuum, It was not easy to remove my thumb from that TB tube as soon as I did it stalled.

Last edited by flmont; 02-23-2020 at 04:44 PM.
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Old 02-26-2020, 10:52 PM   #8
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Yeah, AOS, water pumps etc really are best to use factory parts. Some say aftermarket are fine, but really, given they aren’t the easiest things to swap, why chance it?
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Old 02-29-2020, 02:40 PM   #9
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I bought the porsche factory AOS...would it be easier to pull the oil filler tube to change the AOS unit,.no way my hands can get to the top hose with that tube in the way..?
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Old 02-29-2020, 05:09 PM   #10
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Why yes it is easier to disconnect the oil fill tube,..Aos removed and replaced in the time I asked the oil tube question..!!

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